Patient support apparatuses with navigation and guidance systems

ABSTRACT

Patient support apparatuses, such as beds, cots, stretchers, recliners, or the like, include control systems with one or more image, radar, and/or laser sensors to detect objects and determine if a likelihood of collision exists. If so, the control system controls the speed and steering of the patient support apparatus in order to reduce the likelihood of collision. The control system may be adapted to autonomously drive the patient support apparatus, to transmit a message to a remote device indicating whether it is occupied by a patient or not, and/or to transmit its route to the remote device. The remote device may determine an estimate of a time of arrival of the patient support apparatus at a particular destination and/or determine a distance of the patient support apparatus from the particular destination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.16/549,541 filed Aug. 23, 2019, by inventors Michael Hayes et al. andentitled PATIENT SUPPORT APPARATUSES WITH NAVIGATION AND GUIDANCESYSTEMS, which claims priority to U.S. patent application Ser. No.15/185,067 filed Jun. 17, 2016, by inventors Michael Hayes et al. andentitled PATIENT SUPPORT APPARATUSES WITH NAVIGATION AND GUIDANCESYSTEMS, which claims priority to U.S. provisional patent applicationSer. No. 62/182,911 filed Jun. 22, 2015, by inventors Michael Hayes etal. and entitled PATIENT SUPPORT APPARATUSES WITH NAVIGATION ANDGUIDANCE SYSTEMS, the complete disclosures of all of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates to patient care devices, such as patientthermal temperature management systems, as well as patient supportapparatuses, such as beds, cots, stretchers, recliners, and the like.

Patient support apparatuses are often used to transport individualswithin a healthcare facility, such as a hospital, from one location toanother. In some instances, the patient support apparatuses includebuilt-in propulsion systems that drive one or more wheels on the patientsupport apparatus, thereby reducing the effort a caregiver wouldotherwise have to exert in pushing the patient support apparatus fromone location to another. In other instances, the caregiver is forced tosupply all of the motive force for moving the patient support apparatusfrom one location to another.

SUMMARY

According to various embodiments of the present disclosure, patientsupport apparatuses are provided that include built-in navigation and/orguidance systems. Such built-in navigation and/or guidance systemsenable the patient support apparatuses to perform one or more of thefollowing functions: autonomously drive themselves to destinations;avoid collisions with obstacles; determine their location within afacility in substantially real time (including during transit);communicate with a centralized tracking and scheduling system;automatically recharge their batteries; detect landmarks and/orrecognize features within a particular healthcare facility that enablethe patient support apparatuses to determine their location; and/ortransport patients in a more timely and efficient manner. Otherfunctions may also be performed, either in addition to or in lieu ofthese functions, by different embodiments of the patient supportapparatuses disclosed herein.

According to one embodiment, a patient support apparatus is providedthat includes a frame, wheels, a motor, an actuator, a support surface,an image sensor, and a control system. The motor drives at least one ofthe wheels and the actuator steers the patient support apparatus. Thesupport surface is supported by the frame and adapted to support apatient thereon. The image sensor captures images of an area within afield of view of the image sensor. The control system communicates withthe image sensor and analyzes the images to detect objects within thefield of view. The control system also identifies at least some of thedetected objects, determines a relative velocity of the detected objectsto the patient support apparatus, uses the relative velocity todetermine if any of the detected objects have a likelihood of collisionwith the patient support apparatus that exceeds a threshold, andcontrols the motor and the actuator in order to reduce the likelihood ofcollision below the threshold.

In other embodiments, the control system is adapted to automaticallyidentify walls and floors in the images and to use the identification ofthe walls and floors to autonomously drive the patient supportapparatus.

The control system may also control the actuator in order to reduce thelikelihood of collision by steering away from the one or more objects.

In some embodiments, a user interface is included that allows a user toinput a desired destination of the patient support apparatus within ahealthcare facility. The control system then automatically controls themotor and the actuator such that the patient support apparatus arrivesat the desired destination.

The patient support apparatus may also include an orientation sensor fordetermining an orientation of the patient support apparatus within aframe of reference; a speed sensor for determining a speed of thepatient support apparatus; and a memory having map of a healthcarefacility in which the patient support apparatus is positioned. Thememory includes data sufficient to correlate the frame of reference withthe map. In some embodiments, the image sensor is adapted to detectlandmarks within the healthcare facility and the control system utilizesthe detected landmarks to autonomously drive the patient supportapparatus to a destination. The landmarks may include human readablesigns positioned within the healthcare facility, such as signsindicating room numbers. Other landmarks may also be used.

In some embodiments, the control system analyzes the images to detectobjects by applying one or more of the following to the images: Sobelfiltering, box blurring, Gaussian blurring, convolutional filtering, andmedian filtering. The control system may also include a memory havingobject descriptors stored therein. When so included, the control systemanalyzes the images to determine whether objects corresponding to theobject descriptors are present in the images. In some cases, the objectdescriptors include object descriptors for doors.

An exit detection system may be included with the patient supportapparatus that detects if the patient supported on the support surfacemay be about to exit the patient support apparatus. When included, thecontrol system communicates with the exit detection system and reduces aspeed of the motor if the exit detection system detects that the patientsupported on the support surface may be about to exit the patientsupport apparatus.

In some embodiments, the patient support apparatus includes a memoryhaving dimensions of the patient support apparatus stored therein. Whenso included, the control system utilizes the dimensions in determiningthe likelihood of collision with any of the detected objects.

The patient support apparatus, in some embodiments, includes a secondimage sensor positioned at the patient support apparatus at a knowndistance from—and a known orientation with respect to—the image sensor.When equipped with a second image sensor, the control system determinesdistances between the patient support apparatus and the detected objectsby analyzing the images from both of the image sensors, as well as byutilizing the known distance between, and the known relative orientationof, the two image sensors.

In some embodiments, the actuator for steering the patient supportapparatus is a second motor for driving a second one of the wheels at adifferent speed than the first one of the wheels.

The patient support apparatus may also include a wireless transceiveradapted to receive a wireless message that includes a desireddestination of the patient support apparatus within a healthcarefacility, wherein the control system is adapted to automatically controlthe motor and the actuator such that the patient support apparatusarrives at the desired destination. In some instances, the wirelesstransceiver receives a route and the control system controls the motorand the actuator such that the patient support apparatus follows theroute to the desired destination.

According to another embodiment, a patient support apparatus is providedthat includes a frame, wheels, a motor, an actuator, a support surface,a radar transmitter, a radar sensor, and a control system. The motordrives at least one of the wheels and the actuator steers the patientsupport apparatus. The radar transmitter is adapted to emit radartransmissions and the radar sensor is adapted to detect at least some ofthe reflections of the transmissions from the radar transmitter. Thecontrol system analyzes the reflections to detect objects, to determinea relative velocity of the detected objects to the patient supportapparatus, to use the relative velocity to determine if any of thedetected objects have a likelihood of collision with the patient supportapparatus that exceeds a threshold, and to control the motor and theactuator in order to reduce the likelihood of collision below thethreshold.

In some embodiments, an image sensor is included in addition to theradar transmitter and radar sensor. The image sensor detects landmarkswithin the healthcare facility and the control system utilizes thedetected landmarks to autonomously drive the patient support apparatusto a destination. The landmarks may include human readable signspositioned within the healthcare facility, such as, but not limited to,room numbers.

According to another embodiment, a patient support apparatus is providedthat includes a frame, wheels, a motor, an actuator, a support surface,an image sensor, and a control system. The motor drives at least one ofthe wheels and the actuator steers the patient support apparatus. Theimage sensor captures images of an area within a field of view of theimage sensor, and the control system analyzes the images to detectlandmarks within a healthcare facility. The control system also utilizesthe detected landmarks to autonomously drive the patient supportapparatus to a destination within the healthcare facility.

In other embodiments, the patient support apparatus also includes anorientation sensor, a speed sensor, and a memory. The memory includes amap of the landmarks within the healthcare facility, as well as datasufficient to correlate the frame of reference with the map. The memorymay also include landmark descriptors stored therein that the controlsystem uses when analyzing the images to detect the landmarks. Thelandmark descriptors include, in some embodiments, landmark descriptorsfor colored lines running along a floor or on walls.

In some embodiments, the control system analyzes the images to detectthe landmarks by applying one or more of the following to the images:Sobel filtering, box blurring, Gaussian blurring, convolutionalfiltering, and median filtering.

Some of the embodiments of the patient support apparatus include a lasertransmitter and a laser sensor. The control system is in communicationwith the laser sensor and analyzes reflections of the laser lighttransmitted from the laser transmitter. The control system detectsobjects using the reflection, determines a relative velocity of thedetected objects to the patient support apparatus, uses the relativevelocity to determine if any of the detected objects have a likelihoodof collision with the patient support apparatus that exceeds athreshold, and controls the motor and the actuator in order to reducethe likelihood of collision below the threshold.

According to another embodiment, a patient support apparatus is providedthat includes a frame, wheels, a support surface, a navigation system, awireless transceiver, and a control system. The navigation systemdetects movement of the patient support apparatus within a healthcarefacility. The wireless transceiver communicates with a remote device.The control system communicates with the navigation system and thewireless transceiver, and transmits to the remote device movementinformation that indicates what route was followed by the patientsupport apparatus in moving from a first location to a second location.

Some of the embodiments of the navigation system include anaccelerometer for detecting accelerations of the patient supportapparatus and a magnetometer for detecting a geographical orientation ofthe patient support apparatus. A wheel counting sensor may also, oralternatively, be included that detects revolutions of at least one ofthe wheels. Still further, the navigation system may include analtimeter adapted to detect an elevation of the patient supportapparatus.

The wireless transceiver is a WiFi radio, in some embodiments, and theremote device is a server on a computer network of the healthcarefacility. The control system transmits to the remote device a time whenthe patient support apparatus moved from the first location to thesecond location.

In some embodiments, the memory stores a history of the movement of thepatient support apparatus.

According to another embodiment, a patient support apparatus system isprovided that includes a patient support apparatus and a remote device.The patient support apparatus includes a frame, wheels, a supportsurface, a navigation system, a wireless transceiver, and a controlsystem adapted to transmit both data from the navigation system and aunique identifier corresponding to the patient support apparatus. Theremote device is adapted to receive the data and to determine anestimated time of arrival of the patient support apparatus at aparticular destination within a healthcare facility based upon the data.

The wireless transceiver is a WiFi radio and the remote device is aserver on a computer network of the healthcare facility, in someembodiments. The remote device may also transmit messages over thecomputer network indicating the estimated time of arrival. The messagesare transmitted to a second server on the computer network that isadapted to forward the messages wirelessly to mobile electronic devicescarried by personnel of the healthcare facility. The mobile electronicdevices include cell phones and tablet computers.

The remote device may be adapted to determine a distance traveled by thepatient support apparatus. In some embodiments, the remote devicerepetitively updates and records that distance in memory, and thengenerates an alert message when the distance exceeds a threshold.

The remote device keeps track of a current location of a plurality ofpatient support apparatuses, as well as an availability of the pluralityof patient support apparatuses for transporting patients, in someembodiments. The remote device may determine, out of the plurality ofpatient support apparatuses, the closest currently available one to aselected location.

According to another embodiment, a patient support apparatus system isprovided that includes a plurality of patient support apparatuses and aremote device. The patient support apparatuses each include a frame,wheels, a support surface, a navigation system, a wireless transceiver,and a control system. The control system transmits data from thenavigation system and a unique identifier of the patient supportapparatus to the remote device. The remote device receives the data fromthe patient support apparatuses and determines distances of each of thepatient support apparatuses from a selected location within a healthcarefacility.

In some embodiments, the remote device is further adapted to receiveinformation indicating which of the patient support apparatuses arecurrently available for transporting a patient and to determine whichone of the available patient support apparatuses is closest to theselected location. In some embodiments, the information indicating whichof the plurality of patient support apparatuses are currently availablefor transporting a patient is transmitted by the patient supportapparatuses themselves to the remote device.

In some embodiments, the remote device transmits routing instructions tothe closest available patient support apparatus, which uses the routinginstructions to drive itself to the selected location.

In some embodiments, the patient support apparatuses transmit messagesto the remote device indicating that they are unavailable for transportwhen the charge status of their batteries falls below a threshold. Suchpatient support apparatuses may be configured to autonomously drivethemselves to a battery charging location when the charge status oftheir batteries decreases below the threshold.

The remote device, in some embodiments, includes a user interfaceadapted to allow a user to select one of the plurality of patientsupport apparatuses. Once selected, the remote device summons theselected patient support apparatus to the selected location within thehealthcare facility. The remote device may also be configured to allowthe user to choose the selected location. The user interface may be partof an electronic mobile device carried by the user that is in wirelesscommunication with the remote device.

In another embodiment, a patient support apparatus is provided thatincludes a frame, wheels, a support surface, a patient presencedetector, a wireless transceiver, and a control system. The patientpresence detector detects whether or not a patient is present on thesupport surface. The wireless transceiver transmits to a remote device amessage indicating whether or not the patient is currently present onthe support surface or not.

In some embodiments, the control system includes a drive subsystemadapted to operate in an autonomous mode and the control systemautomatically prevents the drive subsystem from operating in theautonomous mode when the patient presence detector indicates that thepatient is currently present on the support surface.

The patient support apparatus may also be adapted to receive a summonsfrom the remote device to drive to a selected location, wherein thedrive subsystem drives the patient support apparatus to the selectedlocation in the autonomous mode so long as a patient is currently notpresent on the support surface.

In other embodiments, the control system also receives data via thewireless transceiver indicating whether or not any patient is currentlyassociated with the patient support apparatus or not. The control systemautomatically prevents the drive subsystem from operating in theautonomous mode when the patient presence detector indicates that thepatient is currently present on the support surface, or when the dataindicates that the patient is currently associated with the patientsupport apparatus.

The patient support apparatus may also include a bumper adapted todetect contact between the patient support apparatus and an object andto provide an indication to the control system when such contact isdetected. The control system reduces a speed of the patient supportapparatus when such contact is detected.

According to yet another embodiment, a patient support apparatus isprovided that includes a frame, wheels, a support surface, an imagesensor, and a control system. The image sensor captures images of anarea within its field of view. The control system analyzes the images todetect objects, to identify at least some of the detected objects, todetermine a relative velocity of the detected objects to the patientsupport apparatus, to use the relative velocity to determine if any ofthe detected objects have a likelihood of collision with the patientsupport apparatus that exceeds a threshold, and to provide an indicationto a user of the patient support apparatus that a collision may beimminent.

The control system may be adapted to vary the indication depending uponwhere on the patient support apparatus the collision is likely to occur.

In some embodiments, the control system is adapted to identify walls andfloors in the images and to determine a likelihood of collision with thewalls.

Before the various embodiments disclosed herein are explained in detail,it is to be understood that the claims are not to be limited to thedetails of operation or to the details of construction and thearrangement of the components set forth in the following description orillustrated in the drawings. The embodiments described herein arecapable of being practiced or being carried out in alternative ways notexpressly disclosed herein. Also, it is to be understood that thephraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the claims to any specific order or number of components. Norshould the use of enumeration be construed as excluding from the scopeof the claims any additional steps or components that might be combinedwith or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of an illustrativepatient support apparatus that may incorporate aspects of the presentdisclosure;

FIG. 2 is a block diagram of various components of the patient supportapparatus of FIG. 1 ;

FIG. 3 is a block diagram of the patient support apparatus of FIG. 2with more detail regarding a particular navigation system of the patientsupport apparatus, as well as the remote devices with which the patientsupport apparatus communicates;

FIG. 4 is a block diagram of a patient support apparatus according to asecond embodiment of the present disclosure;

FIG. 5 is a block diagram of one embodiment of a landmark/objectdetection system that may be used with the patient support apparatus ofFIG. 4 ;

FIG. 6 is a process diagram illustrating a plurality of processing stepsthat are carried out by the landmark/object detection system of FIG. 5 ;

FIG. 7A is an illustrative image of a hallway that may be captured by animage sensor of the landmark/object detection system of FIG. 5 ;

FIG. 7B is a diagram corresponding to the image of FIG. 7A after havingbeen processed by one or more edge detection algorithms;

FIG. 8 is a block diagram of a first ranging subsystem that is usablewith the patient support apparatus of FIG. 4 ;

FIG. 9 is a block diagram of a second ranging subsystem that is usablewith the patient support apparatus of FIG. 4 ; and

FIG. 10 is a diagram of a patient support apparatus system according toanother embodiment of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A patient support apparatus 20 according to one embodiment of thepresent disclosure is shown in FIG. 1 . Patient support apparatus 20, asshown in FIG. 1 , is implemented as a stretcher. It will be understood,however, that patient support apparatus 20 can be alternativelyimplemented as a bed, a cot, a recliner, or other apparatus that iscapable of supporting a person. Further, it will be understood that someof the embodiments of the present disclosure discussed herein canalternatively be incorporated into other types of patient care devices,such as, but not limited to, temperature management systems forcontrolling the temperature of patients and/or medical carts used totransport items used in conjunction with the treatment of patients. Onesuch temperature management system is disclosed in commonly assignedU.S. patent application Ser. No. 14/282,383 filed May 20, 2014 byinventors Christopher J. Hopper et al. and entitled THERMAL CONTROLSYSTEM, the complete disclosure of which is hereby incorporated hereinby reference.

Patient support apparatus 20 of FIG. 1 includes a base 22 having aplurality of wheels 24, a pair of lifts 26 supported on the base, aframe or litter 28 supported by the lifts 26, and a deck 30 that issupported on top of litter 28. Deck 30 supports a mattress 32, or othercushioning device, on which a patient may sit or lie. A top side ofmattress 32 provides a support surface 34 for the patient.

Base 22 includes a plurality of brake pedals 36 that are adapted toselectively lock and unlock wheels 24 so that, when unlocked, patientsupport apparatus 20 may be wheeled to different locations. Lifts 26 areadapted to raise and lower frame 28 with respect to base 22. Lifts 26may be hydraulic actuators, electric actuators, or any other suitabledevice for raising and lowering frame 28 with respect to base 22. Insome embodiments, lifts 26 are operable independently so that theorientation of frame 28 with respect to base 22 can also be adjusted.

Support deck 30 is made of a plurality of sections, some of which arepivotable about generally horizontal pivot axes. In the embodiment shownin FIG. 1 , support deck 30 includes an upper or head section 38 and alower or foot section 40. Head section 38, which is also sometimesreferred to as a Fowler section, is pivotable between a generallyhorizontal orientation (shown in FIG. 1 ) and a plurality of raisedpositions (not shown in FIG. 1 ).

A plurality of side rails 42 (FIG. 1 ) may also be coupled to frame 28.If patient support apparatus 20 is a bed, there may be four such siderails, one positioned at a left head end of frame 28, a secondpositioned at a left foot end of frame 28, a third positioned at a righthead end of frame 28, and a fourth positioned at a right foot end offrame 28. If patient support apparatus 20 is a stretcher, such as shownin FIG. 1 , or a cot, there may be fewer side rails, such as one siderail 42 on each side of patient support apparatus 20. In otherembodiments, there may be no side rails on patient support apparatus 20.Regardless of the number of side rails, such side rails are movablebetween a raised position in which they block ingress and egress intoand out of patient support apparatus 20, and a lowered position in whichthey are not an obstacle to such ingress and egress.

The construction of any of base 22, lifts 26, frame 28, support deck 30,and/or side rails 42 may take on any known or conventional design, suchas, for example, those disclosed in commonly assigned, U.S. Pat. No.7,395,564 issued to McDaniel et al. and entitled ARTICULATED SUPPORTSURFACE FOR A STRETCHER OR GURNEY, or commonly assigned U.S. Pat. No.6,230,343 issued to Buiskool et al. and entitled UNITARY PEDAL CONTROLFOR HEIGHT OF A PATIENT SUPPORT, the complete disclosures of both ofwhich are incorporated herein by reference. The construction of any ofbase 22, lifts 26, frame 28, support deck 30, and/or the side rails 42may also take on forms different from what is disclosed in theaforementioned patents.

Patient support apparatus 20 also includes a user interface 44positioned at a foot end 50 of support deck 30 (FIG. 1 .). Userinterface 44 includes a plurality of buttons 46 and/or other controlsthat allow a user to control various powered and/or electronic functionsof patient support apparatus 20. For example, user interface 44 may beconfigured to allow a user to control lifts 26 in order to change theheight of support deck 30. User interface 44 may also include controlsfor controlling an exit detection system (discussed in greater detailbelow). Still further, in at least some embodiments, user interface 44includes a display 48, such as, but not limited to, a Liquid CrystalDisplay (LCD), as well as controls for entering alphanumeric data into acontrol system of patient support apparatus 20.

In some embodiments, patient support apparatus 20 also includes at leastone powered wheel 24 a that is selectively driven by one or more motors.This reduces the amount of force required by a caregiver to push patientsupport apparatus 20 from one location to another. A pair of handles 52positioned at a head end 54 of patient support apparatus 20 is used tocontrol the driven wheel. That is, when a user pushes forward (in adirection from head end 54 toward foot end 50) on handles 52, drivenwheel 24 a drives patient support apparatus 20 in a forward direction.When a user pulls on handles 52 in a rearward direction, driven wheel 24a is braked and/or driven in a rearward direction. Further details ofvarious embodiments of powered patient support apparatuses that can bedriven to different locations are disclosed in commonly assigned U.S.Pat. No. 6,772,850, issued to Waters et al. and entitled POWER ASSISTEDWHEELED CARRIAGES, as well as U.S. patent publication 2014/0076644published Mar. 20, 2014 by inventors Richard Derenne et al. and entitledPOWERED PATIENT SUPPORT APPARATUS, the complete disclosure of which ishereby incorporated herein by reference.

FIG. 2 illustrates several of the internal components of patient supportapparatus 20 that are not visible in FIG. 1 . These components includean off-board communication module 56, a controller 58, a navigationsystem 60, and an exit detection system 62. Off-board communicationmodule 56 is adapted to wirelessly communicate with at least one remotedevice 64. Remote device 64 may be a server on a computer network of thehealthcare facility in which patient support apparatus 20 is located.Alternatively, remote device 64 may be a server, or other computerdevice, that is located geographically remote from the healthcarefacility in which patient support apparatus 20 is located, but incommunication with patient support apparatus 20 via an Internetconnection between the remote device 64 and the computer network of thehealthcare facility (which patient support apparatus 20 communicateswith via module 56). In some embodiments, off-board communication module56 is a WiFi transceiver that is adapted to communicate using the WiFiprotocol (e.g. any of the IEEE 802.11 standards) with one or morewireless access points of the healthcare facility's computer network. Inother embodiments, off-board communication module 56 may utilize adifferent communication protocol, such as ZigBee (e.g. IEEE 802.15.4),or another communication protocol. In still other embodiments,communication module 56 may be configured to communicate using multipledifferent communication protocols.

Controller 58 (FIG. 2 ) is in communication with off-board communicationmodule 56, navigation system 60, user interface 44, and exit detectionsystem 62. Controller 58 processes the data received from each of thesecomponents and forwards, as appropriate, commands to one or more of theother components based upon the received data. In general, controller 58oversees the operation of components 56, 60, 44, and 62, and coordinatescommunication between these components.

Controller 58 may take on a variety of different forms. In oneembodiment, controller 58 is any one of the i.MX family ofsystem-on-chip (SoC) processors, or any one of the Kinetis K60 family ofmicrocontroller units (MCUs), both of which are marketed by FreescaleSemiconductor of Austin, Tex. Other types of commercially availablemicrocontrollers may also be used. Still further, controller 58 may takeon still other forms, such as any combination of any one or moremicroprocessors, microcontrollers, field programmable gate arrays,systems on a chip, volatile or nonvolatile memory, discrete circuitry,and/or other hardware, software, or firmware that is capable of carryingout the functions described herein, as would be known to one of ordinaryskill in the art. Such components can be physically configured in anysuitable manner, such as by mounting them to one or more circuit boards,or arranging them in other manners, whether combined into a single unitor distributed across multiple units. The instructions followed bycontroller 58 in carrying out the functions described herein, as well asthe data necessary for carrying out these functions, are stored in oneor more accessible memories (not shown).

Navigation system 60 may take on a variety of different forms, some ofwhich are described in greater detail below. In general, navigationsystem 60 is adapted to determine the location of patient supportapparatus 20 within the healthcare facility when patient supportapparatus 20 is mobile, as well as when patient support apparatus 20 isstationary. In some embodiments, navigation system 60 is also adapted tomaintain a log of the locations that patient support apparatus 20 hastraveled to within the healthcare facility. The log, in addition to thelocations that patient support apparatus 20 has traveled to, includestime stamps for the locations. In other embodiments, the log ismaintained partially or wholly at the remote device 64. In suchembodiments, navigation system 60 communicates the data it generates tooff-board communication module 56, which forwards the data to remotedevice 64. Various uses of the logged data are described in more detailbelow.

Exit detection system 62, when armed, is adapted to issue an alert(audio and/or visual; and local and/or remote) when it detects that anoccupant of patient support apparatus 20 may be about to, or alreadyhas, exited from patient support apparatus 20. In some embodiments, exitdetection system 62 includes a plurality of load cells that detectforces due to the patient's weight while positioned on support surface34. Exit detection system 62 may take on any of the forms, and includeany of the features, of those exit detection systems described incommonly assigned U.S. Pat. No. 5,276,432 issued to Travis and entitledPATIENT EXIT DETECTION MECHANISM FOR HOSPITAL BED; or commonly assignedU.S. patent application Ser. No. 14/212,367 filed Mar. 14, 2014 byinventors Michael Joseph Hayes et al. and entitled PATIENT SUPPORTAPPARATUS WITH PATIENT INFORMATION SENSORS; commonly assigned U.S.patent application Ser. No. 62/065,242 filed Oct. 17, 2014 by inventorsMarko N. Kostic et al. and entitled PERSON SUPPORT APPARATUS WITH MOTIONMONITORING; commonly assigned U.S. patent application Ser. No.14/692,871 filed Apr. 22, 2015 by inventors Marko N. Kostic et al. andentitled PERSON SUPPORT APPARATUS WITH POSITION MONITORING; or commonlyassigned U.S. patent application Ser. No. 62/076,005 filed Nov. 6, 2014by inventors Marko N. Kostic et al. and entitled EXIT DETECTION SYSTEMWITH COMPENSATION, the complete disclosure of all of which areincorporated herein by reference.

In some embodiments, exit detection system 62 also functions as apatient presence detection system. That is, when the load cells detectweight on deck 30 that is greater than an amount of weight expected dueto mattress 32 and its associated bedding, exit detection system 62informs controller 58 that a patient is present on patient supportapparatus 20. In some embodiments, such as those discussed below withrespect to patient support apparatus 220, controller 58 is configured toprevent the patient support apparatus 220 from driving itselfautonomously while a patient is present, as will be discussed in greaterdetail below. In still other embodiments, the patient support apparatusis adapted to receive a message from an off-board device, such as anAdmission, Discharge, and Tracking (ADT) computer on the healthcarefacility's network that indicates whether or not a patient is currentlyassigned to that particular patient support apparatus. When a patient iscurrently assigned, controller 58 is configured, in some embodiments, toprevent the patient support apparatus from driving itself autonomously.

FIG. 3 shows in greater detail one illustrative embodiment of navigationsystem 60 of patient support apparatus 20, as well as variousalternative manners of implementing remote device 64. Navigation system60 of FIG. 3 includes a magnetometer 66, one or more accelerometers 68,a speed and/or direction sensor 70, and an altimeter 72. Thesecomponents all communicate with controller 58. Magnetometer 66repetitively determines the geographical orientation of patient supportapparatus 20 with respect to the Earth's magnetic field and communicatesthis information to controller 58. The accelerometers 68 detectaccelerations of patient support apparatus 20, including both themagnitude and direction of the accelerations. In at least oneembodiment, navigation system 60 includes accelerometers 68 that detectaccelerations in both X and Y directions, where the labels “X” and “Y”refer to two orthogonal directions that are parallel to a horizontalplane. For example, in one embodiment, the X direction refers to thedirection extending from head end 54 to foot end 50 of patient supportapparatus 20, while the Y direction refers to the direction extendingfrom a left side of patient support apparatus 20 to a right side, orvice versa. In still other embodiments, navigation system includes athird accelerometer that detects accelerations in a Z direction (e.g. upand down).

Regardless of the specific number of accelerometers 68, controller 58integrates the outputs of the accelerometers 68 to determine an estimateof the speed and direction in which patient support apparatus 20 ismoving. Controller 58 uses this information, along with headinginformation from the magnetometer, to determine and maintain an estimateof patient support apparatus 20's current location within the healthcarefacility. Alternatively, in some embodiments, controller 58 forwardsthis information to remote device 64, which uses this information todetermine and maintain an estimate of patient support apparatus 20'scurrent location within the healthcare facility. In still otherembodiments, both patient support apparatus 20 and remote device 64maintain an estimate of the current location of patient supportapparatus 20 within the healthcare facility.

Speed and direction sensors 70 (FIG. 3 ) provide an additional source ofinformation for determining the location of patient support apparatus20, as well as tracking its movement throughout the healthcare facility.That is, in addition to the speed and direction information generatedfrom magnetometer 66 and accelerometers 68, speed and direction sensors70 provide a second source of such information. In at least oneembodiment, speed and direction sensors 70 include one or more wheelencoders that measure the number of rotations of one or wheels 24,including the direction in which the wheels rotate. From thisinformation, along with knowledge of the circumference of wheels 24,controller 58 (and/or remote device 64) determines an estimate of thechange in the location of patient support apparatus 20 (i.e. how farpatient support apparatus 20 has traveled and in what direction(s)). Thespeed and direction information provided by accelerometers 68 may becombined with the speed and direction information from sensors 70 in anysuitable manner. In at least one embodiment, the data from these twosources is combined using a Kalman filter, although other techniques maybe used.

In addition to the relative changes in position detected byaccelerometers 68 and sensors 70, patient support apparatus 20 may beconfigured to receive occasional updates of its absolute location withinthe healthcare facility by the detection of one or more fixed locators,or by other means. The occasional updating of the absolute position ofthe patient support apparatus 20 within the healthcare facility allowscontroller 58 and/or remote device 64 to remove errors in the positionestimate of patient support apparatus 20 that accumulate over time, dueto the accumulation of the errors in the signals from the sensors 68and/or 70.

In one embodiment, the absolute position of patient support apparatus 20is provided by fixed locators that comprise wall mounted beacons thattransmit a short range message with a unique ID. The location of each ofthese wall mounted beacons is surveyed and stored in a memory (either onboard patient support apparatus 20 and/or at remote device 64). Becausethe beacons only transmit over a very short range, the detection oftheir short range messages by communication module 56 means that patientsupport apparatus 20 is currently located essentially at the location ofthe beacon (or within a few feet of the beacon).

Examples of such an absolute positioning system, as well as otherpossible alternatives, are described in more detail in commonly assignedU.S. Pat. No. 8,319,633 issued Nov. 27, 2012 to David Becker et al. andentitled LOCATION DETECTION SYSTEM FOR A PATIENT HANDLING DEVICE, aswell as commonly assigned U.S. patent application Ser. No. 62/145,276filed Apr. 9, 2015 by inventors Michael Hayes et al. and entitledLOCATION DETECTION SYSTEMS AND METHODS, the complete disclosures ofwhich are hereby incorporated herein by reference. Other types ofabsolute position updates may also be possible, including, but notlimited to, those disclosed in commonly assigned U.S. patent applicationSer. No. 14/559,458 filed Dec. 3, 2014, by inventors Michael Hayes etal. and entitled PATIENT SUPPORT APPARATUS COMMUNICATION SYSTEMS, thecomplete disclosure of which is hereby incorporated herein by reference.

Patient support apparatuses 20 may utilize still other types of absolutepositioning systems in order to supplement the relative movementinformation provided by sensors 68 and 70. In some embodiments, as willbe discussed in greater detail below, the patient support apparatuses 20are equipped with image sensors and/or laser sensors that are adapted todetect landmarks within the healthcare facility. By correlating thesedetected landmarks to an electronic map of the locations of theselandmarks, controller 58 is able to periodically determine its absoluteposition within the healthcare facility. Still other types of absolutepositioning structures may be used.

Navigation system 60 allows patient support apparatus 20 and/or remotedevice 64 to track the movement of patient support apparatus 20throughout the healthcare facility. More specifically, using the sensorinformation from navigation system 60, controller 58 and/or remotedevice 64 is able to determine the coordinates of patient supportapparatus 20 within the healthcare facility, the direction in which itis traveling, and the velocity of such travel. In some embodiments, thisinformation is communicated wirelessly to remote device 64. Remotedevice 64 includes an integrated floor plan and is in communication withhospital staff so that the current locations of each patient supportapparatus 20, as well as their current movement, can be communicated tothe hospital staff.

FIG. 3 also illustrates in greater detail one manner in which one ormore remote devices 64 may be implemented for communication with patientsupport apparatuses 20. As shown therein, remote device 64 includesthree separate components: a server 64 a that executes a server softwareapplication 74; a mobile electronic device 64 b that executes ahealthcare staff software application 76; and a computer 64 c that alsoexecutes the healthcare staff software application 76 (or a modifiedversion of it). In some embodiments, healthcare staff softwareapplication 76 is installed on mobile electronic devices 64 b as a cellphone app, while being installed on computers 64 c as a desktop softwareapplication. Other variations of healthcare staff software application76 are also possible.

Server application 74 determines the locations of each patient supportapparatus 20 within the facility, updates those locations as the patientsupport apparatuses 20 move, and maintains a log of their locations overtime. Server application 74 communicates all or a portion of thisinformation to one or more staff devices (e.g. mobile device 64 b andcomputer 64 c) via healthcare staff application 76.

In at least one embodiment, server application 74 correlates thelocation information of each patient support apparatus 20 with theidentity of the patients that are assigned to each of these patientsupport apparatuses 20. Application 74 also correlates the identity ofthe patients with the identity of their assigned respective healthcareproviders (e.g. doctors, nurses, physical therapists, etc.). By tyingthe patient and caregiver identities to specific patient supportapparatuses 20 and logging the history of the locations of each patientsupport apparatus 20, application 74 allows the hospital staff to knowimmediately which areas of the hospital may have been exposed toinfectious diseases. That is, application 74 allows authorizedindividuals to access the location histories of each patient supportapparatus 20. From this information, it can be determined where thepatient support apparatus 20 was moved to within the hospital whilebeing assigned to a patient with an infectious disease. This allows thehospital to track what locations are at potential risk for the spreadingof the infectious disease, as well as to take appropriate disinfectingsteps, or other countermeasures, for reducing the risk of the diseasespreading.

In at least one embodiment, application 74 also keeps track of the timesand locations at which patient support apparatus 20 is cleaned. Thisinformation is stored in the data log maintained on board patientsupport apparatus 20 and/or at remote device 64. This information allowshospital staff to identify, using application 76, all of the locationsthat patient support apparatus 20 traveled to between cleanings.

Application 74 also uses the speed and direction information receivedfrom navigation system 60 of patient support apparatus 20 to generateestimated times of arrival of patient support apparatuses 20 at theirdestinations. This allows caregivers and other healthcare staff to moreefficiently coordinate their activities. In at least one suchembodiment, a caregiver is able to access application 76 to determine anestimate of how much time before a particular patient support apparatus20 arrives at the location of that caregiver, or at any other locationthat the caregiver may enter into application 76 using his or her mobileelectronic device 64 b (which may be a smart cell phone, a tabletcomputer, or other mobile electronic device).

Application 74 is also adapted, in at least one embodiment, to provideinformation to users regarding the location of the nearest patientsupport apparatus 20 that is available for transporting a patient. Inone such embodiment, application 76 operates on a cell phone andautomatically utilizes the conventional location services built into thecell phone, or a building specific location app that executes on thecell phone. In another embodiment, application 76 requires a user toenter his or her current location before application 74 determines thenearest available patient support apparatus 20.

When determining the nearest available patient support apparatus 20,application 74 takes into account the floorplans of the healthcarefacility. That is, an electronic map of the floorplan of the healthcarefacility is stored in a memory that is accessible to application 74. Themap includes the locations of walls, obstacles, elevators, doorways, andother aspects of the healthcare facility. Application 74 uses thisinformation to compute the nearest available patient support apparatus20 based upon the actual path the patient support apparatus 20 will haveto follow to a particular location, which may or may not be the closestpatient support apparatus 20 when measured in absolute terms that ignorewalls, obstacles, and the like. In some embodiments, application 74 isconfigured to alternatively, or additionally, determine the nearestavailable patient support apparatus 20 in terms of the estimated amountof time it will take to transport the patient support apparatus 20 tothe desired location. This determination may take into account estimatesof the amount of time it may take for the patient support apparatuses totravel certain pathways, particular in those areas where the estimatedtravel time for the corresponding distance may be larger than theestimated travel time for a similar distance in other areas of thefacility. Such areas may include elevators, areas of heavy traffic orcongestion, or still other areas.

When determining the nearest available patient support apparatus 20,application 74 repetitively receives information regarding which of thepatient support apparatuses 20 are currently available for transportinga patient. Patient support apparatuses are considered “available” whenthey meet certain criteria, which may vary from healthcare facility tohealthcare facility. In general, a patient support apparatus 20 isavailable when it is not currently assigned to a patient, it has beencleaned since being previously used, and, in some cases, its battery—ifit has one—is sufficiently charged. Other criteria may also be used toclassify patient support apparatuses as available.

In at least one embodiment, application 74 communicates with aconventional Admission, Discharge, and Tracking (ADT) system of thehealthcare facility in order to determine which of the patient supportapparatuses 20 are currently assigned to patients. In some embodiments,application 74 may also communicate with a conventional bed or stretchermanagement system of the healthcare facility that keeps track of thecleanliness status of each bed and/or stretcher. Application 74 usesthis information to classify each patient support apparatus 20 into anavailable state or unavailable state.

In still other embodiments, each patient support apparatus 20 includes abutton 46, or other type of control, on its user interface 44 that anauthorized individual presses after the patient support apparatus hasbeen cleaned and is no longer assigned to a patient (and/or after anyother criteria are satisfied that are required before the patientsupport apparatuses 20 are considered available). After such informationis entered into patient support apparatus 20 via user interface 44,controller 58 forwards this information to off-board communicationmodule 56, which transmits the information to remote device 64 a. Serverapplication 74 uses the information to determine the nearest availablepatient support apparatus 20 to any user of remote devices 64 b and/or64 c, which communicate with server application 74 via staff application76.

In order to prevent unauthorized individuals from entering informationinto a patient support apparatus 20 that indicates that the patientsupport apparatus 20 is available, user interface 44 may be configuredto require a code, or other information, before allowing the user todesignate the patient support apparatus 20 as being available. In somesuch embodiments, the user may have to enter a user ID, either manuallyor by swiping his or her employee ID card through a card readerincorporated into the patient support apparatus 20. Still other stepsmay be taken before allowing the user to designate the patient supportapparatus as being available.

In addition to maintaining the current location of patient supportapparatuses 20, application 74 is configured, in at least oneembodiment, to also keep track of the cumulative distance traveled byeach patient support apparatus 20. This information is maintained bysumming the distances between the locations that are repetitivelydetected and reported by each patient support apparatus. Application 74utilizes this information to provide indications to appropriatepersonnel of the healthcare facility of the need to perform maintenancework on the patient support apparatuses 20. That is, when the totaldistance traveled by a patient support apparatus 20 exceeds a threshold,application 74 generates an alert indicating that maintenance should beperformed on that particular patient support apparatus 20. The alert iscommunicated to staff application 76, in at least one embodiment, sothat personnel carrying mobile electronic devices 64 b and/or personnelusing computers 64 c will be alerted to the maintenance needs of thepatient support apparatus 20. In some embodiments, application 74 alsosends the alert to patient support apparatuses 20, which convey thealert to nearby personnel visually and/or aurally.

In still other embodiments, the task of keeping track of the cumulativedistance traveled by a patient support apparatus 20 is carried outlocally on each patient support apparatus 20 by its controller 58. Insuch embodiments, patient support apparatuses 20 include an onboardodometer, or structure capable of performing the same function as anodometer. Further, controller 58 is configured, in some embodiments, tocompare the distance traveled to one or more thresholds, to determinewhether maintenance work is due.

Patient support apparatuses 20 are further configured to allowauthorized individuals to input information—via user interface44—indicating when maintenance work has been performed. This resets thethreshold that the odometer reading (whether maintained locally onpatient support apparatus 20 and/or at server 64 a) is compared to fordetermining when the next routine maintenance is to be performed.

In still other embodiments, when patient support apparatuses 20 includea battery, controller 58 is configured to periodically transmit thecurrent charge status of the battery to server 64 a. Server 64 a usesthis information for at least one of two different purposes. In oneembodiment, server application 74 uses this information as part of thecriteria for determining whether or not a patient support apparatus 20is available for transport. That is, if the battery is not charged abovea threshold, the application 74 considers the patient support apparatus20 as being unavailable for transport (at least until the battery isrecharged). In another embodiment, application 74 uses this informationto alert appropriate personnel that the battery on a particular patientsupport apparatus 20 needs charging. This alerting is done by comparingthe charge level of the battery to a threshold and, if the charge levelis less than the threshold, sending an alert to the staff application76. Staff members who have access to one of the mobile electronicdevices 64 b and/or the computers 64 c will then receive an alertindicating that a patient support apparatus 20 needs to be recharged.The alert will include, in at least one embodiment, a current locationof the patient support apparatus 20 whose battery needs recharging. Instill other embodiments, application 76 utilizes the battery informationin performing both tasks: determining whether the patient supportapparatus 20 is available or not, and determining whether to issue a lowbattery alert or not.

In some instances, patient support apparatuses 20 may also includecircuitry that monitors the health of the battery (in addition to itscurrent charge status). Such monitoring results in an estimate of thecurrent health of the battery, which may indicate when a battery needsto be replaced (as opposed to simply recharged). Examples of such healthmonitoring, as well as circuitry for carrying out this healthmonitoring, are disclosed in commonly assigned U.S. patent applicationSer. No. 62/160,155 filed May 12, 2015 by inventors Aaron Furman et al.and entitled BATTERY MANAGEMENT FOR PATIENT SUPPORT APPARATUSES, thecomplete disclosure of which is hereby incorporated herein by reference.

When one or more patient support apparatuses 20 are configured totransmit battery health information to server 64 a, application 74 usesthis health information in ways similar to the way it uses the batterycharge status information. That is, it uses the health information todetermine the available or unavailable status of a particular patientsupport apparatus 20 and/or it uses the health information to issue analert to appropriate personnel indicating that the battery of aparticular patient support apparatus 20 needs to be replaced.

In all of the communications between patient support apparatus 20 andserver 64 a, it will be understood that patient support apparatus 20transmits a unique ID that distinguishes patient support apparatus 20from other patient support apparatuses, as well as from other medicaldevices that may be in communication with server 64 a. This allowsserver 64 a to sort the messages it receives from the various patientsupport apparatuses 20 according to the sender, as well as to transmitmessages back to specific patient support apparatuses 20.

In some embodiments, staff software application 76 is configured todisplay a map of at least a portion of the floorplan of the healthcarefacility. In addition to the map, application 76 is configured todisplay the locations of the currently available patient supportapparatuses 20. Further, in at least some embodiments, application 76includes user interface features that allow the user to search forpatient support apparatuses 20 using various criteria, such as by thenearest available patient support apparatus, by a specific type ofpatient support apparatus (e.g. bed, cot, or stretcher), by the batterycharge statuses of the patient support apparatuses, by one or morefeatures that are available on the patient support apparatus (e.g. anexit detection system 62, a built-in propulsion system (discussed morebelow), the ability to travel autonomously (also discussed more below)),or by still other criteria. In some embodiments, application 76 isconfigured to also allow searching by combinations of these criteria,thereby enabling the user to search for, as an example, the nearestavailable bed having a built-in propulsion system with a battery that isfully charged.

Once application 76 has identified the patient support apparatuses 20that meet the searcher's criteria, application 76 displays those patientsupport apparatuses 20 on the floorplan map, showing the searcher thelocation of the one or more patient support apparatuses that match hisor her search criteria. In some embodiments, the searcher then walks toa selected one of the identified patient support apparatuses 20. Inother embodiments, as will be discussed in greater detail below,application 76 is configured to allow the searcher to enter a commandthat summons the patient support apparatus 20 to his or her currentlocation or to some other location of the user's choosing. In thoseembodiments, the patient support apparatuses are constructed toautonomously drive themselves to the commanded destination (i.e. drivethemselves without the need for anyone to accompany the patient supportapparatus 20).

FIG. 4 illustrates a patient support apparatus 220 according to a secondembodiment of the disclosure. Those components of patient supportapparatus 220 that are common to patient support apparatus 20, and thatoperate in the same manner, are identified with the same referencenumbers, and are not discussed further in detail below. Those componentsof patient support apparatus 220 that are not found in patient supportapparatus 20 are identified with a new reference number and arediscussed in greater detail below. Patient support apparatus 220 differsfrom patient support apparatus 20 in that it includes an object/landmarkdetection system 80, a drive system 82, and—instead of a navigationsystem 60—a navigation and guidance system 84. Patient support apparatus220 also includes a bumper 86. The function of these additionalcomponents will now be described in more detail.

Object/landmark detection system 80 is configured to detect the presenceof one or more objects 88 (FIG. 4 ) that may be within or near thepathway of patient support apparatus 220. As will be discussed ingreater detail below, when detecting the presence of one or more objects88, system 80 is configured to determine the location of the detectedobject 88 relative to the location of patient support apparatus 220. Insome embodiments, object/landmark detection system 80 is also configuredto identify one or more landmarks 90. Landmarks 90 may take on a varietyof different forms. In some embodiments, landmarks 90 include signspositioned on walls of the healthcare facility (including room numbers),lines or symbols painted on the floor, ceiling structures, elevators,stairways, doors and/or markings on the doors, and still other items. Ingeneral, landmarks 90 are items that are tied to specific locations witha facility, are recognizable by system 80, and typically do not move.Objects 88, in contrast, are not necessarily tied to any particularlocation, may or may not be recognizable by system 80, and may or maynot move.

The identification of a particular landmark 90 provides patient supportapparatus 220 with information about the current location of patientsupport apparatus 220 within the healthcare facility. If the particularlandmark is unique to the healthcare facility, the identification ofthat landmark provides patient support apparatus 220 with an absoluteposition update. When object/landmark detection system 80 detects alandmark, system 80 consults an internal map of the location of thelandmark and determines patient support apparatus 220's absoluteposition within the healthcare facility based upon patient supportapparatus 220's position relative to the landmark. Object/landmarkdetection system 80 then forwards this location information tonavigation and guidance system 84, which uses it to update its estimateof the current location of patient support apparatus 220 within thehealthcare facility.

Navigation and guidance system 84 includes a navigation subsystem thatis, in some embodiments, the same as navigation system 60. Navigationand guidance system 84 also includes a guidance subsystem. The guidancesubsystem allows patient support apparatus 220 to autonomously follow apath or route to an intended destination. That is, guidance subsystemallows patient support apparatus 220 to drive itself to an intendeddestination without the need for a person to accompany patient supportapparatus 220 while it is moving. As discussed more below, suchautonomous guidance enables patient support apparatus 220 to steeritself around obstacles and follow a route to the intended destination.The guidance subsystem also allows patient support apparatus 220 tocontrol its movement in a way that avoids or reduces the likelihood ofcollisions with objects.

Patient support apparatus 220 also includes a drive system 82. Drivesystem 82 includes one or more motors for driving one or more of thewheels 24, as well as one or more motors for steering one or more of thewheels 24. In some instances, patient support apparatus 220 isdifferentially steered by driving two or more wheels at differentspeeds, thereby avoiding the need for a separate steering motor. Someexamples of various forms of drive systems that may be used with patientsupport apparatus 220 are disclosed in the aforementioned commonlyassigned U.S. patent publication 2014/0076644, which was published onMar. 20, 2014, and entitled POWER PATIENT SUPPORT APPARATUS, thecomplete disclosure of which is hereby incorporated herein by reference.Drive system 82 drives patient support apparatus 220 in such a mannerthat it follows a path dictated by the guidance subsystem of navigationand guidance system 84. In some embodiment, the path originates from theguidance subsystem, while in other embodiments, the path is transmittedto patient support apparatus 220 from remote device 64.

Patient support apparatus 220 also includes at least one bumper 86. Insome embodiments, bumper 86 is a passive bumper that merely cushions anyimpact of patient support apparatus 220 against a person or object,thereby decreasing the chances of any injury or damage to either patientsupport apparatus 220 or the impacted person/object. In otherembodiments, bumper 86 is an active bumper that includes sensors fordetecting when it impacts an object. The outputs from the sensors areforwarded to controller 58 that sends commands to drive system 82 tosteer and/or brake patient support apparatus 220 so as to reduce oravoid any further impact. Such active bumpers add an increased level ofsafety for avoiding collisions with objects that may not be detected byobject/landmark detection system 80. Such active bumpers may take on anyof a variety of different forms, including those found in conventionalmaterial handling automatic guided vehicles, some of which aredisclosed, for example, in U.S. Pat. No. 6,739,635 issued to Byun.

Patient support apparatus 220 can also be modified to include a secondbumper. In the embodiment shown in FIG. 4 , patient support apparatus220 includes only a single bumper 86 positioned at a leading end ofpatient support apparatus 220. In some embodiments, however, drivesystem 82 of patient support apparatus 220 is configured to drivepatient support apparatus 220 backward (i.e. in a direction extendingfrom head end 54 toward foot end 50). In such cases, a second bumper 86is positioned at foot end 50 of patient support apparatus 220 isincluded.

FIG. 5 shows in greater detail one illustrative embodiment ofobject/landmark detection system 80. Object/landmark detection system 80includes one or more image sensors 91, a processor 92, a rangingsubsystem 78, and a memory 94. Memory 94 stores the instructionsexecuted by processor 92. Memory 94 also includes a landmark library 96and an algorithm library 98. In at least one embodiment, image sensors91 are cameras, or other light sensing devices that are capable ofcapturing images. In other embodiments, image sensors 91 are two orthree dimensional video cameras. Image sensors 91 are attached topatient support apparatus 20 at any suitable location, and may includemultiple image sensors attached at multiple different locations. Ingeneral, image sensors 91 are attached at locations where a field ofview of the image sensor overlaps with the direction in which thepatient support apparatus is capable of being driven by drive system 82.In at least some embodiments, multiple image sensors 91 are coupled topatient support apparatus 20 at different locations and orientations,and the relative distance between the image sensors 91, as well as theirangular orientation with respect to each other, is used to capturethree-dimensional images.

Processor 92 is programmed to process the images generated by imagesensors 91 and detect objects 88 and/or identify any landmarks 90 thatmay be represented in any of the images. Processor 92 identifieslandmarks 90 by comparing the visual images captured by image sensors 91to information stored in landmark library 96. Landmark library 96includes information stored therein about each of the landmarks 90 thatobject/landmark detection system 80 is adapted to detect. Morespecifically, landmark library 96 includes landmark descriptors such asthe color, size, shape, and location information for each landmark 90.Landmark library 96 may further include any other information about thelandmarks 90 that is useful for processor 92 to identify such landmarkswithin the images generated by image sensors 91.

In processing the images from sensors 91 and identifying any objects 88and/or landmarks 90 that may be present within the images, processor 92is also adapted to utilize a plurality of image processing algorithms.These algorithms are stored in algorithm library 98. In at least oneembodiment, algorithm library 98—and/or other areas of memory94—includes the commercially available software suite referred to asOpenCV (Open Source Computer Vision Library), which is an open sourcecomputer vision library supported by Willow Garage of Menlo Park, Calif.The OpenCV library has been released under the Berkeley SoftwareDistribution (BSD) open source license. The OpenCV library has more than2500 computer vision algorithms and is available for use with variouscommercially available operating systems, including Microsoft Windows,Linux/Mac, and iOS. The OpenCV algorithms include a comprehensive set ofcomputer vision and machine learning algorithms. These algorithms aredesigned to be used to detect and recognize faces, identify objects,classify human actions in videos, track camera movements, track movingobjects, extract 3D models of objects, produce 3D point clouds fromstereo cameras, stitch images together to produce high resolution imagesof entire scenes, find similar images from an image database, follow eyemovements, recognize scenery and establish markers to overlay scenerywith augmented reality, and other tasks.

Any of the major releases of OpenCV (e.g. versions 1.0, 2.0, and 3.0),as well as any one of the multiple intermediate versions, is suitablefor carrying out the features and functions of processor 92 described inmore detail herein. In at least one embodiment of object/landmarkdetection system 80, customized software is added to interact with andutilize various of the software algorithms of the OpenCV library inorder to carry out the features described herein. Other commerciallyavailable software may also be used, either in addition to or in lieu ofthe OpenCV library.

In at least one embodiment, object/landmark detection system 80 includesthe same images sensors, processor, and data libraries as thosedisclosed in commonly assigned U.S. patent application Ser. No.14/578,630 filed Dec. 22, 2014 by inventors Richard Derenne et al. andentitled VIDEO MONITORING SYSTEM, the complete disclosure of which ishereby incorporated herein by reference. In such an embodiment,object/landmark detection system 80 is not only able to detect objectsand landmarks, it is also able to detect their position and distancerelative to patient support apparatus 220.

Ranging subsystem 78 of object/landmark detection system 80 is utilizedin conjunction with the image data gathered from image sensor 91 inorder to determine the distances from the patient support apparatus 220to the objects that appear within the image data. The ranging subsystemcan be implemented in different forms, such as by using infrared, laser,radar, and other technologies. Two different manners for implementingthe ranging subsystem 78 are discussed below in more detail with respectto FIGS. 8 and 9

Processor 92 is programmed to analyze the images detected by sensors 91and take appropriate corrective measures so as to avoid or minimize therisk of patient support apparatus 220 colliding with a person or object.More specifically, processor 92 is adapted to identify objects and/orlandmarks using the image data from image sensors 91, determine thelocation of the objects 88 and landmarks 90 using information fromranging subsystem 78, and report that information to navigation andguidance system 84. The reported information includes the distance ofthe objects 88 and/or landmarks 90 from patient support apparatus 220(such as a predefined reference location on patient support apparatus220), as well as the location of the objects in a coordinate frame ofreference that is correlated with the current position of patientsupport apparatus 220. That is, system 80 reports the location ofobjects 88 and/or landmarks 90 to navigation and guidance system 84either in the same coordinate frame of reference that navigation andguidance system 84 uses to identify the location of patient supportapparatus 220, or with sufficient information to allow navigation andguidance system 84 to convert the location information of objects 88(and/or 90) and patient support apparatus 220 into a common coordinateframe of reference. In this manner, navigation and guidance system 84 isable to determine the relative location of the objects 88 and/orlandmarks 90 to patient support apparatus 220.

In at least one embodiment, object/landmark detection system 80determines the location of each object 88 and landmark 90 by calculatinga distance D (FIG. 4 ) between the object 88 or landmark 90 and areference point on patient support apparatus 220, such as referencepoint 100. In addition to determining the distance D, system 80 alsocalculates the angle of the object 88 or landmark 90 relative to a knownreference line or plane, such as the front end of bumper 86, that passesthrough reference point 100. Thus, in the arbitrary example illustratedin FIG. 4 , object 88 is detected by system 80 to be located at adistance D1 and an angle of A1. This information is reported tonavigation and guidance system 84.

Object/landmark detection system 80 also determines a general shape ofthe objects 88 and landmarks 90. As will be discussed in greater detailbelow, this enables navigation and guidance system 84 to determine ifthere is a likelihood of a collision between patient support apparatus220 and any point on objects 88 or landmarks 90. In other words,navigation and guidance system 84 takes into account not only thelikelihood of colliding with the center of the object or landmark, butalso the likelihood of colliding with any other points on the objects orlandmarks. When so adapted, in the arbitrary example of FIG. 4 ,object/landmark detection system 80 detects the location of landmark 90as extending between a first location identified by distance D2 andangle A2 and a second location identified by distance D3 and angle A3.Other forms of identifying the space occupied by objects 88 and/orlandmarks 90 may be used.

In most embodiments, object/landmark detection system 80 also determinesinformation about the shape and position of objects 88 and landmarks 90in a vertical direction. That is, system 80 also determines, not onlythe height of objects 88 and/or landmarks 90, but any variation in theshape of the horizontal cross sections of the object or landmark atdifferent heights. In this manner, for example, object/landmarkdetection system 80 is able to determine whether or not an object 88,for example, has a footprint on the floor that is uniform throughout theentire height of the object 88, or that varies. This determination canbe especially useful for some objects such as tables, which may occupyrelatively small amounts of space at their leg or legs, and much largeramounts of space at their top surfaces. By determining this information,navigation and guidance system 84, as discussed below, takes steps tomitigate the risk of collisions between patient support apparatus 220and any portion of the detected object 88 (not just those portions atthe ground level, or some other discrete height). Object/landmarkdetection system 80 therefore not only passes information about thehorizontal angles of the position of an object 88 to navigation andguidance system 84, but also passes information about vertical angles ofthe position of the object. Further, in some cases, system 80 passes tonavigation and guidance system 84 a set of data that defines all of thevisible outside edges of the object 88 (both horizontally andvertically) so that navigation and guidance system 84 knows the entirevisible shape of the object 88 (or landmark 90), and can compare this tothe known dimensions and shape of patient support apparatus 220 so as todetermine a likelihood of a collision.

Object/landmark detection system 80 also uses landmark library 96 andalgorithm library 98 to determine whether any detected objects 88 can becategorized as landmarks 90. That is, system 80 compares the image datacaptured from image sensors 91 to the image attribute data stored inlibrary 96 of known landmarks. If system 80 does not find a match, thenthe object remains classified as an object 88. If system 80 determinesthat there is a match, however, then system 80 classifies the object asa landmark.

When object/landmark detection system 80 classifies an object as alandmark 90, it determines the location of the identified landmark 90and forwards it to navigation and guidance system 84, as mentionedpreviously. In addition, system 80 determines if the identified landmark90 is a landmark that is a potential collision risk or not. For example,some landmarks 90 include signs positioned on walls, room numberspositioned on or adjacent doors and doorways, lines or symbols paintedon the floor or walls (or otherwise affixed thereto), and/or other typesof indicia that do not present a collision possibility. When system 80identifies a landmark 90 as something that is not a collision risk, ittransmits this information to navigation and guidance system 84 and, asa result, navigation and guidance system 84 does not issue any motioncommands to drive system 82 that seek to avoid the landmarks 90. Inother words, navigation and guidance system 84 only steers and drivespatient support apparatus 220 (via drive system 82) in a manner thatavoids objects 88 and landmarks 90 that are collision risks, and ignoreslandmarks 90 that are not collision risks (at least as far as motioncommands are concerned)

After receiving the location and shape information regarding objects 88and/or landmarks 90, navigation and guidance system 84 uses thisinformation to calculate an estimate of the probability of patientsupport apparatus 220 colliding with one or more of the objects 88and/or one or more of the landmarks 90 that are collision risks. Incalculating the probability, navigation and guidance system 84 utilizesnot only the location of objects 88 and landmarks 90, but also thecurrent speed and heading of patient support apparatus 220. The speedand heading information comes from sensors contained with the navigationsubsystem (e.g. one or more magnetometers, accelerometers, speed anddirection sensors, and/or altimeters). In calculating this probabilityof a collision, navigation and guidance system 84 also utilizesinformation about the shape and dimensions of patient support apparatus220. More specifically, navigation and guidance system 84 utilizes theshape and dimensions of patient support apparatus 220 in order todetermine if any corner, edge, or other portion of patient supportapparatus 220 is likely to collide with any portion of the object 88and/or landmark 90.

This means, for example, that system 84 may determine that thelikelihood of patient support apparatus 220 colliding with a leg of atable is low, but that the likelihood of colliding with the surface ofthe table (whose edges stick out farther than the legs) is high. In sucha case, navigation and guidance system 84 takes steps to reduce thisrisk, as will be discussed more below.

In at least some embodiments, navigation and guidance system 84 alsotakes into account a weight of a patient, or other objects, that arepositioned on support surface 34 when calculating a likelihood ofcollision, and/or when determining an appropriate measure to reduce thelikelihood of collision. In such embodiments, patient support apparatus220 is equipped with a built-in scale system that measures the weight ofthe patient, or other objects supported on surface 34. This weight isused to estimate how much force will be needed to stop, slow, and/orchange the direction of patient support apparatus 220. That is, thegreater the measured weight, the more mass that must be accelerated ordecelerated, and the acceleration or deceleration of more mass requiresgreater force. Navigation and guidance system 84 will therefore outputcommands to drive system 82 that are adjusted based upon differingamounts of force needed due to different weight being carried by patientsupport apparatus 220.

In calculating the probability of a potential collision with an object88 or landmark 90, navigation and guidance system 84 is configured, inat least one embodiment, to also utilize the rates of change of thespeed and direction of patient support apparatus 220. That is, inaddition to the speed and direction in which patient support apparatus220 is currently traveling, navigation and guidance system 84 utilizesmeasurements of the change in the speed and direction of patient supportapparatus 220. This allows navigation and guidance system 84 to takeinto account any steering (changes in direction) that drive system 82 iscurrently undertaking, as well as any acceleration or decelerations. Insome embodiments, system 84 alternatively—or additionally—takes intoaccount the rate of change of the relative speed between patient supportapparatus 220 and each of the detected objects 88, as well as the rateof change of the relative angular orientation between patient supportapparatus 220 and each of the detected objects 88. This enablesnavigation and guidance system 84 to better account for movements ofobjects 88.

Regardless of the specific factors utilized by navigation and guidancesystem 84 in determining a probability of a collision with object 88 orlandmark 90, navigation and guidance system 84 compares the determinedprobability to a threshold. If the probability exceeds a threshold,navigation and guidance system 84 issues motion commands to drive system82 that change the speed and/or direction of patient support apparatus220. The motion commands are generated in a manner that reduces thelikelihood of collision. The motion commands include braking, steering,and acceleration.

After issuing one or more motion commands to drive system 82, navigationand guidance system 84 processes another set of data received fromobject/landmark detection system 80 about the position, orientation, andshape of objects 88 and landmarks 90. In other words, object/landmarkdetection system 80 repetitively captures images of objects 88 andlandmarks 90 and analyzes these images in the manner discussed above.The results of these repeated image analyses are forwarded to navigationand guidance system 84, which generates repeated motion commands todrive system 82. Collectively, object/landmark detection system 80,navigation and guidance system 84, and drive system 82 therefore operatein a closed loop fashion for collision avoidance. Object/landmarkdetection system 80 provides repetitive feedback to navigation andguidance system 84 about the effectiveness of the previous sets ofmotion commands it forwarded to drive system 82. The motion commandssent to drive system 82 are therefore repetitively updated anddynamically adjusted while an object or landmark is within the field ofview of object/landmark detection system 80.

In addition to controlling the movement of patient support apparatus 220in a manner that it avoids collisions, navigation and guidance system 84is configured to control drive system 82 in such a manner that patientsupport apparatus 220 may be directed to one or more desireddestinations within a healthcare facility. In some embodiments, theguidance subsystem of navigation and guidance system 84 includes a mapof the healthcare facility, and the guidance subsystem uses the map tooutput motion commands to drive system 82 that direct patient supportapparatus 220 toward a desired destination. The motion commands used toguide patient support apparatus 220 to a desired destination areoverridden, temporarily paused, or modified, when an object 88 orlandmark 90 is detected that poses a risk of collision above thethreshold (discussed previously). That is, navigation and guidancesystem 84 alters the steering and driving of patient support apparatus220 so as to avoid a collision, while still directing patient supportapparatus 220 to the desired destination. In some instances, navigationand guidance system 84 may cease all motion of patient support apparatus220 when a mobile object 88 is present until the mobile object is movedout of the way of patient support apparatus 220, at which pointnavigation and guidance system 84 resumes driving patient supportapparatus 220 to the desired destination.

In combination, object/landmark detection system 80, navigation andguidance system 84, and drive system 82 allow patient support apparatus220 to be driven and steered autonomously from one location to anotherwithout the need for a user to carry out this steering and speedcontrol, and indeed without the need for a user to even be present. Inat least one embodiment, patient support apparatus 220 includes withinuser interface 44 one or more buttons 46—or other controls—that enable auser to input the desired destination for patient support apparatus 220and to input a command that then commands patient support apparatus 220to travel autonomously to the desired destination. Navigation andguidance system 84 is also configured to receive desired destinationsfrom mobile electronic devices 64 b and/or from remote computers 64 c.Such devices transmit their commands through server 64 a to off-boardcommunication module 56. When patient support apparatus 220 receives adesired destination from a remote device 64, it transmits periodicupdates of its location back to remote device 64 while traveling to thedesired destination. Patient support apparatus 220 also transmits amessage back to remote device 64 when it arrives at the desireddestination.

FIG. 6 illustrates in more detail a process 113 that is undertaken byprocessor 92 (which may include one or more coprocessors, graphicsprocessors, and/or other processing circuitry). As shown therein, at afirst step 114, processor 92 of object/landmark detection system 80processes and conditions the images captured by image sensors 91.Thereafter, the processed images undergo one or more filteringtechniques at step 116. After the filtering is performed, processor 92performs at a step 118 one or more edge extraction techniques on theprocessed and filtered image data. After performing the edge extraction,processor 92 transforms and/or classifies features in the processedimage data at a step 120. Finally, at steps 122 and 124, informationindicating which pixels of the image data correspond to objects 88and/or landmarks 90 is extracted from the image data and theidentification and position determining functions mentioned above arecarried out with respect those objects 88 and/or landmarks 90.

When initially processing the image data captured by image sensors 91 atstep 114, processor 92 performs one or more of the following processesusing algorithms stored in algorithm library 98: black level detectionand adjustments, dead pixel detection, exposure detection andadjustments, vignetting detection and adjustments, geometric distortiondetection and correction, high dynamic range rendering, demosaicing, RGB(red, green, blue) to YUV color space conversions, spatial denoising(including salt and pepper noise and Gaussian noise), gamma correction,and image scaling.

After performing one or more of the aforementioned processes at step114, processor 92 applies one or more filters to the image data at step116. Such filters include the Sobel filter or operator, the medianfilter, a histogram median filter, an integral image filter (or summedarea table filter), a finite impulse response (FIR) filter, and a textfilter.

Following the filtering step at 116, processor 92 proceeds to step 118where it applies one or more of the following edge extractiontechniques: Canny edge detection, Histogram of Oriented Gradients (HOG)processing, Features from Accelerated Segment Test (FAST) processing,Binary Robust Independent Elementary Feature (BRIEF) or other binarydescriptor processing, Kirsh operator edge detection, the Harris affineregion detector, and the Shi-Tomasi corner detection algorithm. FIG. 7Aillustrate an arbitrary image captured of a hallway, such as might bepresent in a healthcare facility, prior to processing by processor 92.FIG. 7B illustrates the image of FIG. 7A after one or more edgedetection techniques have been applied. As can be seen therein, firstedges 104 a between a floor 106 and walls 108 are more easily identifiedin FIG. 7B, as well as second edges 104 between walls 108 and ceiling110. The edge detection algorithms applied to FIG. 7B also accentuatethe edges 104 c of a plurality of pictures 112 hanging on walls 108. Insome embodiments, pictures 112 may serve as landmarks 90 with landmarklibrary 96 storing identifying information for each picture 112,including its location within the healthcare facility.

After performing one or more edge detection techniques on the image dataat step 118, processor 92 is also programmed to analyze the image dataat step 120 by using one or more of the following machine learningtechniques: creating and using a Support Vector Machine (SVM) or supportvector network model, creating and using an artificial neural networkmodel, and/or applying naive Bayes classifiers to the processed imagedata. Processor 92 may also be programmed to extract information fromthe image data using logistic regression and/or randomized forestmethods at step 122. Finally, processor 92 may also be programmed tocarry out K-nearest neighbor processing for classifying the image dataand/or restricted Boltzmann machine (RBM) processing of the image dataat step 124.

FIG. 8 illustrates in greater detail one manner in which rangingsubsystem 78 may be implemented on patient support apparatus 220. Morespecifically, ranging subsystem 78 of FIG. 8 includes both short rangeradar and long range radar. As can be seen, the short range radardetects objects within a short area 126 while the long range radardetects objects within a large area 128. The signals emitted by theshort and long range radars that are reflected off of objects aredetected by sensors on board patient support apparatus 220 and processedby ranging subsystem 78 to determine the distance and shape of objects.Processor 92 correlates the distance and shape information received fromranging subsystem 78 with the images captured by image sensors 91. Thisis accomplished in known manners and includes time stamping the imagescaptured by image sensors 91, time stamping the ranging informationreceived from ranging subsystem 78, and knowing the relative positionand angles between the images sensors 91 and the radar sensors on boardpatient support apparatus 20.

FIG. 9 illustrates a patient support apparatus 220 having an alternativeranging subsystem 78 a that may be used instead of subsystem 78. In theembodiment shown in FIG. 9 , patient support apparatus 220 includes afirst ranging subsystem 78 a positioned at the head end of patientsupport apparatus 220 and a second ranging subsystem 78 a positioned atthe foot end of patient support apparatus 220. The following descriptionof ranging subsystem 78 a applies to both the head end and foot endsubsystems 78 a.

Ranging subsystem 78 a utilizes on-board laser emitters and sensors todetect the distances, shapes, and relative locations of the objects andlandmarks 88 and 90 with respect to patient support apparatus 220. Thatis, processor 92 processes the reflections of the laser beams todetermine the location, shape, and dimensions of any objects 88 and/orlandmarks 90 that are within the field of view of the laser emitters.Each ranging subsystem 78 a includes at least one laser emitter 130 andone or more laser sensors 132. Each laser sensor 132 includes a sensorfield of view 134. Laser emitters 130 emit laser beams having outgoingtracks 136 and, when encountering an object 88, return tracks 138.Ranging subsystem 78 a determines a distance to the object 88 bysubtracting the time of emission of an outgoing laser track 136 from thetime of arrival of the reflected or returning laser track 138. This timedifferential is converted to an estimate of distance based upon theknown speed of light.

Laser emitters 130 are configured to emit outgoing tracks 136 atdifferent angles so that objects 88 positioned at any location near theforward or rearward ends of patient support apparatus 220 can bedetected. The distance and location information detected by rangingsubsystem 78 of objects 88 or landmarks 90 is utilized by processor 92to correlate with pixel data from the images from image sensors 91 todetermine the distance and locations of objects within the pixel data.In other words, processor 92 identifies objects and landmarks 90 usingimage data from image sensors 91, and determines the distance andlocation of those objects relative to patient support apparatus 220using the ranging information gathered from ranging subsystem 78 a.

Processor 92 also utilizes and compares successive ranging measurementsand/or successive captured images to determine the relative speed of thedetected objects 88 or landmarks 90 with respect to patient supportapparatus 220 is determined by processor 92. As described previously,knowing the relative speed and direction of the detected objects 88 orlandmarks 90 with respect to patient support apparatus 220, along withthe dimensions of the objects 88, landmarks 90, and patient supportapparatus 220, navigation and guidance system 84 determines whatactions, if any, to take to reduce the risk of a collision.

In at least one embodiment, pulse repetition frequencies are used withthe emitted laser beams in order to allow for tracking of each laserbeam and for easy discrimination between signals. The laser emitters 130emit laser beams in an arc pattern at both the front and rear ends ofpatient support apparatus 220. System 80 discriminates between thedetected backscatter and other reflections via amplitude and pulse timeof arrival differences. The software executed by processor 92 alsoallows for organization and discrimination between valid tracked objectsand backscatter and reflections. With data from the navigation subsystemof the navigation and guidance system 84, navigation and guidance system84 is able to determine an estimated time of impact with the detectedobject (assuming no changes are made to the movement of patient supportapparatus 220 through motion commands to drive system 82). Navigationand guidance system 84 uses this information to determine what motioncommands to send to drive system 82 in order to reduce or eliminate thelikelihood of a collision with the object 88 (or landmark 90).

FIG. 10 illustrates in greater detail one embodiment of a patientsupport apparatus system 150 that may be utilized in a healthcarefacility. Patient support apparatus system 150 includes a plurality ofpatient support apparatuses. For purposes of visual and descriptiveconvenience, the patient support apparatuses of FIG. 10 have all beenlabeled with the reference number 220 and are referenced herein with thereference number 220. It will be understood, however, that some or allof the patient support apparatuses of FIG. 10 could alternatively beimplemented as patient support apparatuses that are different from thepatient support apparatuses 220 described previously.

As is often the case in many healthcare facilities, the healthcarefacility itself includes one or more charging areas 152 where thebatteries of the patient support apparatuses 220 are charged. Typicalhealthcare facilities may also include one or more transport offices154, maintenance areas 156, patient rooms 158, and MRI areas 160, aswell as still other types of areas not shown in the illustrative exampleof FIG. 10 . Typical healthcare facilities also include a healthcarecomputer network (not shown), such as, but not limited to, one or moreEthernets. Further, the healthcare computer network often includes aplurality of wireless access points 162 that enable mobilesdevices—including patient support apparatuses 220—to communicate withthe healthcare computer network using WiFi and/or other wirelesscommunication protocols. System 150 also includes a remote device, suchas server 64 a, that is in communication with the healthcare facilitynetwork. Patient support apparatuses 220 are able to communicate withserver 64 a, and vice versa, via the healthcare computer network, thewireless access points 162, and the wireless off-board communicationmodules 56 included with each patient support apparatus 220.

Patient support apparatus system 150 is designed to provide valetfunctionality to caregivers and other personnel of the healthcarefacility with respect to the patient support apparatuses 220. System 150therefore allows authorized personnel to summon a patient supportapparatus 220 to a desired location utilizing server 64 a directly, ormore typically, utilizing a device that is in communication with server64 a, such as a mobile electronic device 64 b and/or a computer 64 cthat is part of the healthcare facility network. System 150 includes allof the functionality previously described regarding summoning patientsupport apparatuses, identifying available patient support apparatuses(including the nearest one), estimating times of arrival, and showinglocations of the patient support apparatuses on maps.

In a first embodiment of system 150, the summoning of patient supportapparatuses 220 takes place via initial communication with patienttransport office 154. That is, in this first embodiment, the need for apatient support apparatus 220 is first communicated to office 154. Thiscommunication may occur via a telephone call to a person working inoffice 154, or via an electronic transmission to a computer positionedin office 154 that the person has access to (e.g. an email, text,instant message, or still other means). However communicated, the personin office 154 responds to the request for a patient support apparatus220 by utilizing a software program on the computer in office 154 thatis in communication with server 64 a (the software program, in at leastone embodiment, is staff application software 76). The software enablesthe person in office 154 to inquire about currently available patientsupport apparatuses 220 that can be directed to the desired location.Server 64 a responds to this request with a list of patient supportapparatuses 220 that are currently available for satisfying the requestfor a patient support apparatus. The person in office 154 then choosesone of the patient support apparatuses 220 from the list, and sends aninstruction to server 64 a instructing it to command the chosen patientsupport apparatus 220 to drive itself to the requested location. In thisfirst embodiment, the selection of patient support apparatuses isfacilitated by server 64 a, but the person or persons in transportoffice 154 ultimately choose how to respond to the incoming requests forpatient support apparatuses 220.

In a second embodiment of system 150, the summoning of patient supportapparatuses 220 occurs automatically without the need for any manualaction by a person in office 154. In this embodiment, a person desiringa patient support apparatus 220 makes a request for a patient supportapparatus 220 using his or her mobile electronic device 64 b or a nearbycomputer 64 c. The request is then forwarded directly to server 64 a,which determines which patient support apparatuses are available fortransport, selects one, and commands the selected one to move to therequested location.

In either the first or second embodiments, after a patient supportapparatus 220 has responded to a request, and after the patient supportapparatus 220 has finished transporting a patient to a desired location,system 150 is adapted to automatically command the patient supportapparatus 220 to travel to a cleaning area, such as maintenance area156. To the extent the battery on board the patient support apparatus220 has drained below a threshold charge level, server 64 a alsoautomatically commands the patient support apparatus 220 to travel toone of the charging areas 152 to have its battery recharged.

In some embodiments, when server 64 a transmits a command to aparticular patient support apparatus 220 to travel to a desireddestination, server 64 a merely identifies the desired destination tothe patient support apparatus 220 and the patient support apparatus 220consults its own on-board map of the healthcare facility to determine aroute to the commanded destination. The on-board map is stored in amemory of patient support apparatus 220 that is accessible to navigationand guidance system 84. Patient support apparatus 220 then follows thechosen route using object/landmark detection system 80 to avoidobstacles and to periodically detect its location within the healthcarefacility as previously described.

In other embodiments, server 64 a determines the route by which patientsupport apparatus 220 is to travel to the desired destination andtransmits this route to patient support apparatus 220. This transmissionmay occur all at once, or it may be sent piecemeal (such as by sendingcommands to patient support apparatus 220 to travel to a first waypoint,and then to a second waypoint, and then to a third, and so on, until thepatient support apparatus 220 reaches the desired destination). Stillother manners for commanding and controlling the routing of patientsupport apparatuses 220 are possible.

In some embodiments of patient support apparatus system 150, patientsupport apparatuses 220 are equipped with dedicated short rangecommunication (DSRC) equipment that enables them to talk directly toeach other in a manner that helps avoid collisions between patientsupport apparatuses. DSRC is primarily designed for use with automobilesand operates in the United States over a 75 MHz spectrum in the 5.9 GHzband (it occupies a 30 MHz spectrum of the 5.9 GHz band in Europe).Among the applications of DSRC that may be applied to patient supportapparatuses 220 are the following: emergency warning systems for patientsupport apparatuses, cooperative adaptive cruise control, cooperativeforward collision warnings, intersection collision avoidance, and anyother forms of collision avoidance.

It will be understood by those skilled in the art that variousmodifications and changes to the patient support apparatuses and patientsupport apparatus systems disclosed herein can be made. For example,navigation system 60 can be incorporated into other devices, such asrecliners and/or thermal control systems. One such suitable recliner isdisclosed in commonly assigned U.S. patent application Ser. No.14/212,253 filed Mar. 14, 2014 by inventors Christopher Hough et al. andentitled MEDICAL SUPPORT APPARATUS, the complete disclosure of which isincorporated herein by reference. One such thermal control system isdisclosed the previously mentioned patent application Ser. No.14/282,383, which has already been incorporated herein by reference.When navigation system 60 is incorporated into recliners and/or thermalcontrol systems (and/or beds, stretchers, cots, or the like), thenavigation system 60 communicates with a remote device, such as server64 a, which monitors, logs, and keeps track of the locations of each ofthe devices having a navigation system 60 on-board.

It will also be understood that, when one or more patient supportapparatuses 20 are implemented as beds, the beds may take on a widevariety of forms. In some embodiments, when the patient supportapparatuses are implemented as beds, they are constructed in any of themanners described in commonly assigned, U.S. Pat. No. 8,689,376 issuedApr. 8, 2014 by inventors David Becker et al. and entitled PATIENTHANDLING DEVICE INCLUDING LOCAL STATUS INDICATION, ONE-TOUCH FOWLERANGLE ADJUSTMENT, AND POWER-ON ALARM CONFIGURATION, and/or any of themanners described in commonly assigned, U.S. patent application Ser. No.13/775,285 filed Feb. 25, 2013 by inventors Guy Lemire et al. andentitled HOSPITAL BED, the complete disclosures of both of which arehereby incorporated herein by reference.

Various additional alterations and changes beyond those alreadymentioned herein can be made to the above-described embodiments. Thisdisclosure is presented for illustrative purposes and should not beinterpreted as an exhaustive description of all embodiments or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described embodiments maybe replaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as an alternative.Any reference to claim elements in the singular, for example, using thearticles “a,” “an,” “the” or “said,” is not to be construed as limitingthe element to the singular.

What is claimed is:
 1. A patient support apparatus system comprising: apatient support apparatus having a frame, wheels, a support surface, anavigation system, a wireless transceiver, and a control system adaptedto transmit data from the navigation system and a unique identifiercorresponding to the patient support apparatus; and a remote deviceadapted to receive the data and to determine an estimated time ofarrival of the patient support apparatus at a particular destinationwithin a healthcare facility based upon the data, wherein the remotedevice is further adapted to perform the following: keep track of acurrent location of a plurality of patient support apparatuses; keeptrack of an availability of the plurality of patient support apparatusesfor transporting patients; and determine, out of the plurality ofpatient support apparatuses, the closest currently available one to aselected location.
 2. The patient support apparatus system of claim 1wherein the wireless transceiver is a WiFi radio and the remote deviceis a server hosted on a computer network of the healthcare facility. 3.The patient support apparatus of claim 2 wherein the server is furtheradapted to transmit messages over the computer network indicating theestimated time of arrival.
 4. The patient support apparatus of claim 3wherein the messages are transmitted to a second server on the computernetwork that is adapted to forward the messages wirelessly to a cellphone carried by a person associated with the healthcare facility. 5.The patient support apparatus system of claim 2 wherein the server isfurther adapted to maintain in memory a history of locations the patientsupport apparatus has traveled to.
 6. The patient support apparatussystem of claim 2 wherein the server is further adapted to determine adistance traveled by the patient support apparatus, and to repetitivelyupdate and to record that distance in memory.
 7. The patient supportapparatus system of claim 6 wherein the server is further configured togenerate an alert message when the distance exceeds a threshold.
 8. Thepatient support apparatus system of claim 1 wherein the wirelesstransceiver is a WiFi radio, the remote device is a server is hosted ona computer network of the healthcare facility, and the server is furtheradapted to transmit messages over the computer network indicating theestimated time of arrival.
 9. A patient support apparatus systemcomprising: a patient support apparatus having a frame, wheels, asupport surface, a navigation system, a wireless transceiver, and acontrol system adapted to transmit data from the navigation system and aunique identifier corresponding to the patient support apparatus; and aremote device adapted to receive the data and to determine an estimatedtime of arrival of the patient support apparatus at a particulardestination within a healthcare facility based upon the data; whereinthe navigation system of the patient support apparatus further includesan accelerometer for detecting accelerations of the patient supportapparatus, a magnetometer for detecting a geographical orientation ofthe patient support apparatus, and an altimeter adapted to detect anelevation of the patient support apparatus.
 10. A patient supportapparatus system comprising: a patient support apparatus having a frame,wheels, a support surface, a navigation system, a wireless transceiver,and a control system adapted to transmit data from the navigation systemand a unique identifier corresponding to the patient support apparatus;a remote device adapted to receive the data and to determine anestimated time of arrival of the patient support apparatus at aparticular destination within a healthcare facility based upon the data;and an image sensor positioned at the patient support apparatus, theimage sensor adapted to capture images of an area within a field of viewof the image sensor; wherein the control system is adapted to analyzethe images to detect landmarks within the healthcare facility and toutilize the detected landmarks to autonomously drive the patient supportapparatus from its current location to the particular destination. 11.The patient support apparatus system of claim 10 wherein the wirelesstransceiver is a WiFi radio, the remote device is a server hosted on acomputer network of the healthcare facility, the server is adapted totransmit messages over the computer network to a second serverindicating the estimated time of arrival, and the second server isadapted to forward the messages wirelessly to a cell phone carried by aperson associated with the healthcare facility.
 12. A patient supportapparatus system comprising: a plurality of patient support apparatuses,each having a frame, wheels, a support surface, a navigation system, awireless transceiver, and a control system adapted to transmit data fromthe navigation system and a unique identifier corresponding to each oneof the plurality of patient support apparatuses; and a remote deviceadapted to receive the data from the plurality of patient supportapparatuses and to determine distances of each of the patient supportapparatuses from a selected location within a healthcare facility, theremote device further adapted to receive information indicating which ofthe plurality of patient support apparatuses are currently available fortransporting a patient and to determine which one of the availablepatient support apparatuses is closest to the selected location.
 13. Thepatient support apparatus system of claim 12 wherein the plurality ofpatient support apparatuses are adapted to be steered and drivenautonomously.
 14. The patient support apparatus system of claim 12wherein the information indicating which of the plurality of patientsupport apparatuses are currently available for transporting a patientis transmitted by the patient support apparatuses to the remote device.15. The patient support apparatus system of claim 14 wherein the remotedevice is adapted to summon the closest available patient supportapparatus to the selected location.
 16. The patient support apparatussystem of claim 15 wherein the remote device is adapted to generate anestimated time of arrival of the summoned patient support apparatus tothe selected location.
 17. The patient support apparatus system of claim12 wherein the patient support apparatuses include batteries, thecontrol systems are adapted to monitor a charge status of the batteries,and the patient support apparatuses are adapted to transmit messages tothe remote device indicating that they are unavailable for transportwhen the charge status of their batteries falls below a threshold. 18.The patient support apparatus system of claim 12 wherein the wirelesstransceiver is a WiFi radio and the remote device is a server on acomputer network of the healthcare facility.
 19. A patient supportapparatus system comprising: a plurality of patient support apparatuses,each having a frame, wheels, a support surface, a navigation system, awireless transceiver, and a control system adapted to transmit data fromthe navigation system and a unique identifier corresponding to each oneof the plurality of patient support apparatuses; and a remote deviceadapted to receive the data from the plurality of patient supportapparatuses and to determine distances of each of the patient supportapparatuses from a selected location within a healthcare facility,wherein the remote device includes a user interface adapted to allow auser to select one of the plurality of patient support apparatuses, andthe remote device is further adapted to summon the selected patientsupport apparatus to the selected location within the healthcarefacility.
 20. The patient support apparatus system of claim 19 whereinthe user interface is further adapted to allow the user to choose theselected location, and wherein the user interface includes an electronicmobile device carried by the user that is in wireless communication withthe remote device.